Не понятно, почему не принимает решение.
package com.javarush.task.task19.task1907;
/*
Считаем слово
*/
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader ( new InputStreamReader ( System.in ) );
StringBuilder sb = new StringBuilder ( );
FileReader fileReader = new FileReader ( reader.readLine () );
reader.close ();
while (fileReader.ready()) sb.append ( (char) fileReader.read () );
fileReader.close ();
System.out.println (sb.append("\0").toString ().toLowerCase ().split ( "world" ).length - 1);
}
}